Title: Voltage imaging analysis of striatal network dynamics related to movement, Parkinson?s disease and deep brain stimulation Summary Deep brain stimulation (DBS) delivers high frequency electrical current stimulation through chronically implanted electrodes. DBS has been FDA approved for managing several brain disorders, including Parkinson?s disease (PD), epilepsy, essential tremor, and obsessive compulsive disorders. However, the therapeutic mechanisms of DBS remain largely unknown. There are many intriguing hypothesis, but experimental evidence has been limited. The increasing use of DBS for PD over the past 20 years has offered a unique opportunity to record from various basal ganglia brain structures in patients, and accumulating evidence suggests that exaggerated pathological local field potential (LFP) beta oscillations (~10-30Hz) in the cortical-basal ganglia circuit are a signature of PD. Using exaggerated LFP beta oscillations recorded in STN as a target feature, a recent study showed that closed-loop DBS could be more effective in alleviating akinesia in primate PD models, highlighting the potential of using pathological beta oscillations as a biomarker for PD. PD is characterized by degeneration of SNpc dopamine neurons that project to the striatum. The fact that DBS is effective at managing motor pathologies highlights that PD involves neural circuit deficits that can be altered by electrical stimulation to achieve therapeutic effects. The central goal of this proposal is to study the neural circuit dynamics related to PD, and the therapeutic mechanisms of DBS, using a novel single cell voltage imaging technique that was recently developed in Dr. Han?s lab. Specifically, we will examine how individual striatal neurons? subthreshold membrane voltage and spiking patterns relate to bulk striatal LFP oscillations during voluntary movement in healthy and dopamine-depleted PD conditions, and how DBS alters these interactions. Such understanding will provide important insights into the relationship between individual neurons subthreshold membrane voltage dynamics (a measure of synaptic inputs) and spiking outputs, and provide direct experimental evidence linking pathological LFP oscillations with single neuron biophysics, and how DBS affects these relationships. We believe that such insights will help establish oscillation based biomarkers for brain disorders, and facilitate future DBS designs.